PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma

Lab Invest. 2019 Oct;99(10):1418-1427. doi: 10.1038/s41374-019-0262-5. Epub 2019 Jun 13.

Abstract

Targeting the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway represents a milestone in cancer therapy. However, the biologic features of diffuse large B-cell lymphoma (DLBCL) with PD-L1 expression remains unknown. We evaluated the correlation between pSYK and PD-L1 mRNA levels with RNAscope in situ hybridization and protein levels with immunohistochemistry in 108 cases of DLBCL, 25 of which featured loss of B-cell receptor (BCR), and investigated the effects of BCR signaling and MYC on PD-L1 mRNA and protein level with qPCR, immunoblotting and flow cytometery in DLBCL cell lines. PD-L1 amplification was detected with fluorescent in situ hybridization. Animal studies were applied to validate the in vitro findings. pSYK and MYC correlated with both PD-L1 mRNA and protein level. Genetic aberrations involving PD-L1 were rare in DLBCL. BCR signaling and MYC increased PD-L1 mRNA and protein expression. Inhibition of BCR signaling and BCR knockdown down-regulated PD-L1. DLBCL with a loss of loss of BCR showed low levels of PD-L1 mRNA and protein. PD-L1 was down-regulated by ibrutinib in a xenograft mouse model and correlated with slower tumor growth. In conclusion, this study demonstrates that DLBCL with PD-L1 expression features an activated B-cell receptor signal pathway, and that BCR inhibition and PD-L1 blockage may potentially synergize to targeting DLBCL.

MeSH terms

  • Adenine / analogs & derivatives
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • B7-H1 Antigen / metabolism*
  • Female
  • Humans
  • Lymphoma, Large B-Cell, Diffuse / metabolism*
  • Male
  • Mice, SCID
  • Middle Aged
  • Piperidines
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Pyrazoles
  • Pyrimidines
  • Receptors, Antigen, B-Cell / metabolism*
  • Retrospective Studies
  • Signal Transduction
  • Syk Kinase / metabolism
  • Young Adult

Substances

  • B7-H1 Antigen
  • CD274 protein, human
  • Cd274 protein, mouse
  • Piperidines
  • Proto-Oncogene Proteins c-myc
  • Pyrazoles
  • Pyrimidines
  • Receptors, Antigen, B-Cell
  • ibrutinib
  • Syk Kinase
  • Adenine